The way his schedule is laid out, yes, I believe it is not in S4's best interest to switch off every other day one week and then 4 nights in a row another.
There are way too many transitions back and forth during the actual week for his age. He really is having a hard time knowing if he is coming or going. Always asking me "where am I going?" My IC has a lot of training in counseling young children and agrees that at 4 years old he is too young for the bouncing back and forth.
Did I answer your question?
Almost. What I was trying to get you to say was something like, "he is too young for the bouncing back and forth because ...." and then fill in the blank. Because his dad lives in a tiny house and his homework requires him to build full scale models of Roman ruins nightly. Because his dad won't take him to school--ever, and he'll miss 64 days this year. Because he doesn't understand the concept of schedules and screams unceasingly for six hours straight when it doesn't turn out like he thought. My point is.....just because he asks where he's going doesn't meant it's detrimental to him. That's totally normal for a kid his age, D or not.
Don't misunderstand me, I'm not challenging your schedule, nor am I proposing anything else. I'm just challenging you to clarify your position, understand where these feelings are coming from. For your sake as much as S's.